Turbomachines, such as steam turbines, gas turbines, compressors, pass through several transient operating modes before operating under nominal conditions. During all operating modes, including nominal operating conditions, critical structural vibrations may occur.
These structural vibrations may cause damages or reduce the lifetime of certain machine components, if not adequately dampened.
For the purpose of protecting sensitive components against disruptive structural vibrations it is generally known in the field of machine engineering to apply wire mesh elements for insulating or damping such disruptive vibrations. In addition, wire mesh elements provide a certain shock resistance and a thermal resistance up to more than 1000° C.
Wire meshes are made from continuous or quasi-continuous wire in the form of intermeshing stitches. The extremely small contact surfaces at the contact points in combination with captured air in the cavities ensure low heat transfer rates. The meshwork is three-dimensionally flexible and provides good elasticity and stretching characteristics.
FIG. 1 shows a typical structure of a vibration insulating and damping element 300. Core piece of such an insulating and damping element 300 is a wire mesh element (cushion) 200. FIG. 1 illustrates a one-piece wire mesh element 200.
Such types of insulating and damping elements 300 are broadly used for vibrations insulating or damping bearings of machines, e.g. as a base for pedestals of vibrating machines. Regularly, these insulating/damping elements 300 consist of round or rectangular (not shown) cushions 200 made of woven compressed stainless steel wire, inserted into a complementary shaped housing 320. The cushion 200 may be equipped with a central bore 310 for the machine pedestal or a screw or bolt to mount the machine on the bottom. A base plate 330 with screw holes 340 for screwing the damping element on a base may exist. The housing 320 is connected either with the base plate 330 or with the machine pedestal.
Document US 2009/0304313 A1 describes a compliant hybrid gas journal bearing, including compliant hybrid bearing pads having a hydrostatic recess and a capillary restrictor for providing a flow of pressurized gas to the bearing. The bearing also includes an inner rim adjacent the bearing pads, an outer rim and a damper bridge between the inner and outer rims. The damper bridge has an axial length that is less than an axial length of the bearing pads and the outer rim to form a damper cavity on each side of the damper bridge. An integral wire mesh damper is situated within the damper cavity on each side of the damper bridge. Integral centering springs are located between the inner and outer rims to provide radial and rotational compliance to the bearing pads. The oil-free bearing design addresses the low damping and low load capacity characteristics that are inherent in present day compliant air foil bearing designs, while retaining the compliance to changes in rotor geometry.
EP 0 989 289 A1 describes a vibration-decoupling joint of the type in which two annular end pieces, sealingly fixable to respective opposite portions of a pipe to be connected, are connected to each other by a first metal bellows-shaped sleeve, elastically deformable and which connects the end pieces with a fluid-tight seal, and by a second metal sleeve defining a part that mechanically supports the connection, located radially outside of the bellows sleeve and the end pieces, fitted axially over these latter; a first end piece has an internal flow-guide element shaped to define a cantilevered portion of duct that extends axially with radial play into the first metal sleeve and towards the second end piece, starting from the first end piece and extending in the direction of flow until it reaches the second end piece; the flow guide element is formed from an annular plug in the form of a pipe formed from wire mesh, constituted by a tubular metal sock folded to form multiple radial layers and made from stainless steel wire braided to form a linked mesh.
The cited state of the art does not disclose or suggest the use of wire mesh elements as damping means in connection with a turbomachine, especially in connection with a thermally loaded component of a gas turbine.